1. Field of the Invention
The invention relates to a cosmetic and/or dermatological composition in the form of a powder containing pulverulent ascorbic acid, a starch and at least one anionic surfactant. This composition is useful, for example, for cleansing the skin, both of the body and of the face, including the area around the eyes and the scalp. The invention also relates to a use of this composition for cleansing and/or treating the skin, as well as to a cosmetic process for cleansing and/or treating the skin.
2. Description of the Background
It has been sought for a long time to formulate ascorbic acid, or vitamin C, in the cosmetic and dermatological fields in different pharmaceutical forms, on account of its many beneficial properties. In particular, ascorbic acid stimulates the synthesis of connective tissue and especially of collagen, it reinforces the skin tissue defences against external attacking factors such as ultraviolet radiation and pollution, it compensates for a vitamin E deficiency in the skin, it depigments the skin, and it has an anti-free-radical activity.
Unfortunately, on account of its chemical structure (an xcex1-keto lactone), ascorbic acid is very sensitive to certain environmental parameters such as light, oxygen and water. This results in rapid degradation of the formulated ascorbic acid when it is in contact with one of these parameters, which is counter to the desired efficacy for treating skin. Moreover, in order to make use of the beneficial effects of ascorbic acid in a skin cleansing composition, it is also necessary for the composition containing it to have good foaming properties without destabilization of the ascorbic acid.
Several solutions have already been envisaged to reduce and/or delay the degradation of ascorbic acid. One of the solutions consists in particular in using ascorbic acid in powder form and in dissolving it in water immediately before use. JP-A-01-079,105 describes a powder based on ascorbic acid for topical application. However, on account of the high acidity of the solution obtained, it is corrosive and runs the risk of causing serious skin irritation. In addition, such a composition has no foaming properties.
There is thus still a need for a composition containing ascorbic acid, which can be stored for several years before being used, while at the same time having good foaming properties when used.
The inventor has now found a cosmetic and/or dermatological composition which overcomes the drawbacks of compositions containing ascorbic acid described above.
Accordingly, it is an object of the present invention to provide a composition suitable for cosmetic and/or dermatologic use, containing:
pulverulent ascorbic acid,
a starch, and
at least one anionic surfactant,
where the composition is in the form of a powder.
It is another object to providing a method of treating skin by applying the inventive composition to the skin.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description.
The inventive composition is in the form of a powder, i.e. in the form of a solid finely divided into particles with an average particle size ranging, for example, from 50 to 600 xcexcm and preferably from 150 to 400 xcexcm. These particle sizes include all specific values and subranges therebetween, including 75, 100, 125, 175, 200, 250, 300 and 350 xcexcm.
The powder obtained is prepared by simple mixing of the pulverulent constituents; it is thus easy to manufacture. In addition, it has excellent solubility in water and good foaming properties. Moreover, it is pleasant to use on the skin on account of its softness.
As will be recognized by one skilled in the art, the inventive composition may contain small amounts of water, as long as the composition retains its powder form.
The pulverulent ascorbic acid sold by, for example, Hoffmann-La Roche can be used, as the pulverulent ascorbic acid. The ascorbic acid is present in the composition of the invention in an amount ranging, for example, from 0.1 to 20%, and preferably from 0.5 to 10%, of the total weight of the composition. These ranges include all specific values and subranges therebetween, including 1, 2, 3, 5, 8, 12, 15 and 18% by weight of the total composition.
The nature of the starch in the inventive composition may vary widely. The starch may be, for example, from rice starch, corn starch, wheat starch, potato starch, oat starch, tapioca starch and mixtures thereof. It may be natural or modified.
According to a preferred embodiment of the invention, the starch is a modified starch, and, in particular, a crosslinked starch. This modified starch can be selected, for example, from starches crosslinked with a functional group, for example starches crosslinked with octenylsuccinic anhydride and more particularly xe2x80x9caluminium starch octenyl succinatexe2x80x9d, such as the product sold by National Starch under the name Dry-Flo, or the crosslinked corn starch sold under the name Resistamyl E2 by Amylum; starches modified in terms of the amylose/amylopectin ratio, such as the product Hylon VII sold by Amylum; modified starches such as the weakly quaternized corn starch sold under the name Myplus W7 by Amylum, the potato starch sold under the name Supramyl P 60 by Amylum, or the hydroxypropyl corn starch sold under the name Merigel EF6 by Amylum.
The starch is present in the composition in an amount which can vary over a wide range. Thus, this amount can range, for example, preferably from 10 to 90%, and more particularly from 30 to 60%, of the total weight of the composition. These ranges include all specific values and subranges therebetween, such as 15, 20, 25, 35, 40, 50, 70, 75, 80 and 85% by weight.
The nature of the anionic surfactant used in the composition according to the invention may vary widely in the context of the present invention. Thus, as examples of anionic surfactants which can be used, alone or as mixtures, in the context of the present invention, mention may be made in particular of salts (particularly alkaline salts, especially sodium salts, ammonium salts, amine salts, amino alcohol salts or magnesium salts) of the following compounds: alkyl sulphates, alkyl ether sulphates, alkylamido ether sulphates, alkylarylpolyether sulphates, monoglyceride sulphates, alkyl sulphonates, alkyl phosphates, alkylamide sulphonates, alkylaryl sulphonates, xcex1-olefin sulphonates, paraffin sulphonates, alkyl sulphosuccinates, alkyl ether sulphosuccinates, alkylamide sulphosuccinates, alkyl sulphosuccinamates, alkyl sulphoacetates, alkyl ether phosphates, acyl sarcosinates, acyl isethionates and N-acyl taurates, the alkyl or acyl radical of these various compounds preferably containing from 12 to 20 carbon atoms, and the aryl radical preferably denoting a phenyl or benzyl group.
Among the anionic surfactants which can also be used, mention may also be made of fatty acid salts such as oleic, ricinoleic, palmitic and stearic acid salts and salts of coconut oil or of hydrogenated coconut oil; acyl lactylates in which the acyl radical contains 8 to 20 carbon atoms.
Among these anionic surfactants, it is more particularly preferred to use isethionate salts such as sodium cocoyl isethionate; glutamate salts such as sodium lauroyl glutamate and the product sold under the name xe2x80x9cAmisoft HS-11xe2x80x9d by Ajinomoto (CTFA name: xe2x80x9csodium hydrogenated tallow glutamate); sarcosinate salts such as the stearoyl sarcosinate/myristyl sarcosinate mixture; alkyl sulphate salts such as sodium lauryl sulphate and its derivatives; alkyl ether sulphate salts such as sodium laureth sulphate; sulphosuccinate salts such as disodium laureth sulphosuccinate and disodium MEA sulphosuccinate; taurate salts such as sodium methyl cocoyl taurate; xcex1-olefin sulphonate salts such as sodium C14-C17 sec-alkyl sulphonate; alaninate salts such as sodium lauroyl methylaminopropionate; sodium lauryl sulphoacetate, as well as mixtures thereof.
Other anionic surfactants which may be used in the inventive composition are described in International Cosmetic Ingredient Dictionary and Handbook, Volume 2, Seventh Edition, 1997, pp. 1673-1690, incorporated herein by reference.
The anionic surfactant is present in the composition according to the invention in an amount which can vary within a wide range. Thus, this amount can range, for example, from 10 to 80%, and preferably from 30 to 50%, of the total weight of the composition. These ranges include specific values and subranges therebetween, such as 15, 20, 25, 35, 40, 60, 70 and 75% by weight.
According to one specific embodiment of the invention, the composition also comprises at least one water-soluble polymer. This water-soluble polymer can be selected in, particular, from polysaccharides, synthetic polymers, celluloses and clays.
As examples of water-soluble polymers which can be used in the invention, mention may be made of guar gum, xanthan gum, carrageenan gum, cellulose gum or sclerotium gum, derivatives of these gums, hydroxyalkylcelluloses, sodium carboxycelluloses, polyacrylamides and acrylamide copolymers, gelatin, agar-agar, carboxyvinyl polymers (carbomer), montmorillonite and magnesium aluminium silicate.
The amount of polymer in the composition of the invention can range, for example, from 1 to 5%, and preferably from 2 to 3%, of the total weight of the composition. These ranges include all specific value and subranges therebetween such as 1.5, 2.5 and 3.5% by weight.
The composition of the invention may contain additives other than those mentioned above and which are generally used in the cosmetic and dermatological fields, such as, for example, sequestering agents, fragrances, antioxidants, water-soluble active agents, preserving agents, dyestuffs (such as pigments and hydrophilic dyes) and inorganic and/or organic fillers. These additives can be present in the final composition in an amount of from 0 to 50%, preferably from 0.5 to 20% and even more particularly between 0.5 and 10%, of the total weight of the composition. These ranges include all specific values and subranges therebetween, such as 0.75, 1, 2, 5, 12, 15, 25, 30, 40 and 45% by weight.
Of course, a person skilled in the art will take care to select the optional additives and/or the amounts thereof such that the advantageous properties intrinsically associated with the composition in accordance with the invention are not, or are not substantially, adversely affected by the addition(s) envisaged.
As active agents, mention may be made, for example, of softeners such as allantoin, moisturizers such as glycerol and sugars, enzymes and vitamins, and exfoliants such as polyethylene powders and apricot kernel powder.
As fillers, mention may be made, for example, of talcs or magnesium silicate hydrates, micas or aluminosilicates, clays, kaolin or aluminium silicate hydrate, boron nitrides, and acrylic acid or methacrylic acid polymers and copolymers such as the products sold under the name xe2x80x9cPolytrapxe2x80x9d by Dow Corning.
The composition of the invention may be prepared by mixing all of the constituents in a homogenizer, after optionally grinding the powders whose particle size is too large.
The composition of the invention advantageously contains a medium which is physiologically acceptable for the skin, mucous membranes, the nails, keratin fibres and/or the hair.
In a highly preferred embodiment, the composition of the invention gives rise to the formation of a mousse in the presence of water and in particular has good efficacy for cleansing the skin and in all the applications of vitamin C, especially for treating the skin and in particular for toning and regenerating it, for treating wrinkles and/or fine lines on the skin, for lightening the complexion, for removing skin pigmentation marks, for combating the harmful effects of UV radiation and/or for reinforcing skin tissues against environmental attacking factors.
Thus, a subject of the present invention is also a cosmetic use of the composition according to the invention for cleansing the skin, for treating the skin and, in particular, for toning and regenerating it, for treating wrinkles and/or fine lines on the skin, for lightening the complexion, for removing skin pigmentation marks, for combating the harmful effects of UV radiation and/or for reinforcing skin tissues against environmental attacking factors.
A subject of the present invention is also a cosmetic process for cleansing and/or treating the skin, which consists in using the composition according to the invention.
In these applications, the inventive composition is contacted with water to moisten the composition, and then the composition is applied to the skin to be treated. The composition may be applied to the subject by, for example, simply rubbing the compositions on the skin by hand.
According to one specific embodiment of the invention, the composition of the invention is incorporated in a sponge in single-dose form. The sponge is moistened with water and is then passed over the face and rinsed.